A physician knowledgeable in the clinical practice of lymphedema management most often makes the diagnosis of lymphedema through physical examination. Your personal health history also provides excellent clues in diagnosing lymphedema. Radiologic testing is often performed in persons to rule out conditions that may cause swelling; in other words, to rule out causes other than lymphedema.

Some imaging tests help to support the diagnosis of lymphedema, but are not used to diagnosis the disease of lymphedema, which is based on clinical assessment and health history.

An example of an imaging test is lymphoscintigraphy, which involves injecting dye into the lymphatic vessels and then assessing the direction and volume of lymphatic flow. Unfortunately, there are no "normal" results with lymphoscintigraphy, and the results are not detailed, providing little guidance. Most clinical experts who care for persons with lymphedema do not feel that lymphoscintigraphy is helpful or necessary in most cases.

Although MRI's and CT scans can show swelling, these tests are used to rule out injury or the presence of a tumor. Edema (swelling) volume cannot be easily measured through these tests. Doppler ultrasounds assess problems with the venous system, but do not give information concerning lymphatic compromise.